Dental pulp tester



June 11. 1940. R. H. BROCKMAN} 2,204,295

DENTAL PULP TESTER Filed Nov. 29, 1958 2 Sheets-Sheet. 1

l ll 6/ I A9. 36 as 529 Z7 :5

l? L AL 7 :0

'- M n 2.9 "2'2 1 "d /a 20 49 70 84K 73 74 a0 78 77 m v If [i Brock/nan June 11, 1940- I R. H. BROCKMAN 2,204,295

DENTAL PULP TESTER Filed Nov. 29, 1938 2 sneets-snee-z.

F. J. J 58 i c 66 as 60 56 *2 27 1 4 a/ 1 l2 l w 1 4 4 4r ,7 ff

"M y 1 i Patented Junell, v

. UNITED STATES PATENT OFFICE r 2,204,235 DENIAL PULP 'rss'ma Robert H. Brockman, St. Petersburg, Fla. Application November-29, 193a, semi No. 243,002

4 Claims. (01. 128-21) the tooth. Abscesses of this character may not,

cause any local pain or give any external indication of their presence, and'yet may cause a continuous formation of pus which isabsorbed 1 into the system. and may give rise to various ailments such as rheumatism, kidney" disease,

heart disease, etc.

It is the main object of the present invention to provide a pulp testing instrument by means 20 of which a dentist may determine very readily whether degeneration of the nerve of a tooth has set in, and the extent of such degeneration. Another object of the invention is to provide a pulp testing instrument by means of which as the relative extent of nerve degeneration, as compared with a sound tooth, may be indicated visually. Other objects of the invention will become apparent as the detailed description thereof pro- 30 ceeds. 7

In the drawings: Figure 1 is a perspective view of in a casing;

as Figure 2 is an end elevation of the operating mechanism of the tester with a side wall of the casing removed and with parts illustrated in vertical section;

- Figure 3 is a horizontal section taken on the 40 line 3--3 of Figure 2;

Figure 4 is a vertical section taken on the line 4--4 of Figure 3; V

Figure 5 is a wiring diagram; I Figure 6 is a longitudinal section through an 5 electrode-probe adapted to be applied to a tooth undergoing test; 7

Figure '7v is a longitudinal central'section, to a modified form, of the electrode-probe shown in Figure 6; and 50 Figure 8 is a section taken on the line 3-3 Figure 7.

As shown in the drawings, the invention 'in-' cludes a casing, 3 in which is enclosed substantially all of the moving parts of the mechanism.

5 A motor M, suitably secured to the base ll of I the casing, has its rotor shaft l2 provided with a pinion I3 meshing with a spur gear l4 suitably secured to a shaft i5 journalled at its opposite ends in bearing brackets i3 and I1 suitably secured to the base II.' A pinion l3, secured to 6" the shaft l5, meshes'with a large gear [9 which is provided at its center with a circular aperture 20 rotatably receiving a cylindrical projection 2| formed on a collar 22 which is fixed to a shaft 23 by means of a. pin 24 passing through ,r egistering apertures in the said collar 22 and shaft 23.

The cylindrical projection 2| forms on the collar 22 an annular shoulder 25 against which the large gear 19 is frictionally clamped by means of a'cupped washer 26 mounteci'on the shaft 23 ,andcontacting frictionally with one side of the gear l3. 'A compression spring 21 surrounds the shaft 23 and is interposed between the washer 26 and a collar 23 secured to the shaft 23 by means of a pin 29 passing through registering apertures formed-in thesaid shaft 23 and collar .23.

A knurled handle 30 is suitably secured to the outer end of the shaft 23 and has an indicator 25 3| ,extendingradially-therefrom to rotate over a, voltage scale 32 formed on' the front wall 33 of the casing 9. The shaft 23 is journalled on bearinglbrackets 34 and) suitably secured to and extending upwardly from the base H, and 0 Y extends into the casing of .a potentiometer desthe pulp tester with most of the operating parts enclosed ignated generally by the reference numeral 36'. 'Electriccurrent for the motor M and the other parts-of the instrument is derived from the mains -31 and 33. A wire 39, tapped to the main 31, is

' a contact 44 adapted to be moved by the foot of the operator into contact with the fixed contact 40 43 to close the circuit across the mains 31 and 33.

The instrument includes a handle comprising a tube 45 in which isfixed a contact 46 electrically connected to one end of. the main 33. The other main 31 is electrically connected through 45 a sleeve 31.to a contact 41 projecting from the end of a rod 48 suitably secured in one end of an insulating member 49 slidably mounted in the tubular handle 45. This handle 45 is provided with a slotill through which projects a lug 5| 50 extending laterally from the member 49 and through said slot to be engaged by the thumb of the operator.- v

A metallicplug 52, screw-rth'readed into the end 0! the tube 4! remote from the contact 46 and 86 41, is provided with a bore 53 in which a suitable conducting probe 84 may be detachablysecured by means of the set screw IS. A coil spring 58 interposed between the inner end of the plug 52 and theenlarged end of the member 43 main-v tains said member it normally in position to hold the contacts 48 and 41 yieldlngly separated from each other. Itwill be obvious that said contacts 88 and 41 may be moved into contact with each other by pressure of the thumb of the operator upon the lug against the yielding resistance of the spring 56. It will also be apparent then that the motor M may be started either by the foot of the operator pressing upon the spring switch 42, or by the hand of the operator 1 pressing against the projecting lug 5| to close the main around the motor M and the transformer secondary S is connected at one end by a wire 53 to a terminal 60 of the potentiometer 36.

g The other end of the secondary is connected by a wire 6| to the other terminal 82 of the potentiometer 36.

The shaft 28 has a wiper arm 83 secured thereto within the potentiometer casing to rotate over the potentiometer coil 64; and this shaft 23 is electrically connected by wires to the electrode 5!. The terminal 68 of the potentiometer is electrically connected '3 by wire 86 extending lengthwise through the tubular handle of the probe-electrode into contact with the metallic plug 52s The wiper arm 63 and the indicator 3| are fixed to the shaft 23in such manner that when the indicator 3| is set to the zero division on the scale 32, the end of the wiper arm will be located over the terminal 60 of the potentiometer.

The scale 32 is preferably divided into. fifty divisions, each of which represents roughlyone volt, so as to give the operator a definite guide in comparing the relative sensitivities of the teeth undergoing test. Because of the frictional connection between the shaft. 23 and the large gear I9, it will be obvious that the shaft 23 maybe rotated manually in either direction to any desired position on the scale 32. Of course, it is understood that this frictional connection is sufiicient to cause the shaft 23 to be rotated around the scale 32 under control the motor M through the reducing gearing connecting the rotor shaft l2 with the gear l9.

Teeth for testing may be roughly divided into several classes: First-normal teeth, that is, teeth having no fillings and apparently unblemished. Second-teeth that are unblemished, but which are for some reason painful. Thirdteeth with fillings. Fourthworn teeth. Fifthdead teeth; that is, teeth from which the pulp has been removed by a dentist, or in which the pulp has died either from mechanical or chemical or thermal irritation. Of course, there are other classifications; but generally an experienced operator by using the pulp tester described herein can arrive at a good understanding as to the relative health of the nerve in any tooth.

In operating the machine, the patient is seated.

Then the tooth to be tested is cleaned and dried shaft l2 transmits its rotation through the inter-' vening reduction gearing to the potentiometer shaft 23. The current increases as the potentiometer arm and the indicator 3| rotate, respectively, around the potentiometer coil 64 and the scale 32. When sufllcient voltage has been applied to the tooth by this operation to give a reaction, the operator releases the pressure on the lug 5| to stop the motor. Releasing the lug SI, of course, stops the entire mechanism so that no shock is felt by the patient beyond the first slight irritation, which may be the reaction from a normal tooth.

If the tooth is sub-normal or dead, the voltage can be carried to a much higher point before the patient experiences any irritation, due to the passage of current through the tooth; and then it manifests itself at the hand electrode or in the tissues around the tooth. If a tooth .has a filling and the electrode is applied to it, and the tooth is alive or vital, the stimulation is felt at a much lower voltage. Obviously, this is due to the fact that the filling (if a metallic one) conducts the current nearer the pulp and offers much less resistance to the current than the normal toothstructure would oiTer so that the irritation is felt at a lower potential or voltage. In the case of a tooth in which the nerve for some reason is hyper-sensitive, or more sensitive than normal, a response to the current is obtained at a much lower voltage.

The modification of the probe-electrode illustrated in Figures 7 and 8 comprises a tube 68 of insulating material in which is slidably mounted The operator then presses 10 a metallic plug 69 provided with a bore I0 in which a conducting probe H is detachably secured by the set screw 12. The plug 69 is turned down to form a rod 13 of smaller diameter extending axially of. the tube 68. The end of the rod 13 remote from the plug 69 is screw-threaded for connection to an enlargement 14 on the inner end of a conducting rod 15 slidably mounted in a conducting sleeve 16 fixed in a non-conducting plug 11 inserted in the outer enlarged end 18 of the tube 88. Conducting pins I3 and 80 extend through this non-conducting plug 11 into the space in the enlarged end I8 around the rod 15.

The conducting sleeve 16 is connected by the wire 66 to the potentiometer terminal 60; and the conducting pins 19 and 80 are connected, respectively to the main wires 31 and 38. The enlargement M has a shoulder 8| seating an insulating collar 82 provided with an annular rabbet in which is seated a conducting ring 83 adapted to make electrical contact with the pins I9 and 80 when the tube 68 is moved lengthwise of the plug 89 toward the probe II. To secure the probe normally in open circuit position, a collar 84 is suitably secured to the inside of the tube 68 and a stop 85 is secured to the rod 13 to contact with the collar 84 and limit the outward movement of the probe with respect to its While I have shown the electrode 51 as 'a metallic cylinder adapted to be held in the hand of the patient or to be clamped against the patients hand by means of the spring clamp 51', it isto be understood that this description and illustration is merely for convenience in disclosure. The invention is obviously intended to be used by applying the electrode II to any available and suitable part of the patients body. Therefore, in such claims as the second electrode is referred to as adapted to be held in the hand" of a patient, it must be understood that this is merely a convenient way of stating that'the second electrode may be held or otherwise applied to any other part of the human body.

What I claim is:

1. A tooth nerve testing instrument comprising a hollow handle, an electrically conducting probe mounted therein, a single conductor electrically connected to the probe and adapted to constitute one terminal of a secondary electrical circuit, a pair of conducting terminals mounted in insulated relation to each other within the handle and adapted to constitute a switch in a primary electrical circuit, and a movable element enclosed by the handle to open and to close the primary circuit/across the pair of terminals, the probe being movable longitudinally within the handle, an abutment fixed to the interior walls of'the handle, a spring fastened between the probe and the abutment, a rod extending from the probe to the vicinity of the primary terminals carrying a conductor adjacent the terminals and adapted 'to close the primary terminals when the probe former having primary and secondary circuits connected with the tooth testing instrument and means in the primary circuit and actuated by the primary current to alter the secondary circuit voltage. r

2. A tooth nerve testing instrument comprising a hollow handle, an electrically conducting probe mounted therein, a single conductor electrically;

be obvious from;this construcinterconnected by a transformer,

handle to open and to constituteone terminal is moved into the handle, and a transconnected to the probe and adapted to constitute one terminal of a secondary electrical circuit, a pair of conducting terminals mounted in insulated relation to each other within 'the handle and adapted primary electrical circuit, and a movable element enclosed by the handle to open and to close the primary. circuit across the pair of terminals, and, exterior to the handle and connected therewith, a primary circuit and a secondary circuit sistance in the secondary circuit, and means operated by flow of current in the primary circuit to vary the secondary resistance continuously when the primary circuit is closed. g

3. A tooth' nerve testing instrument comprising a hollow handle, an electrically conducting probe mounted therein, a single conductor electrically connectedto the probe and adapted to constitute one terminal of a secondary electrical circuit, a pair of conducting terminals mounted in insulated relation to each other within, the handle and adapted to constitute a switchin a primary electrical circuit, an element movable within the close the primary circuit exterior to the ciracross the pair of terminals, and, handle and connected therewith, a primary cult, and a secondary circuit interconnected by variable resistance in the secflow of a transformer, ondary circuit and means operated by to constitute a switch in a variable recurrent in the primary circuit to vary the secondary resistance continuously when the primary circuit is closed, and a foot switch in the primary circuit in parallel with the terminals in the handle of the testing instrument.

4. A tooth nerve testing instrument comprising a hollow handle, an electrically conducting probe mounted therein, a single conductor electrically connected to the probe and adapted to of a secondary electrical circuit, a pair of conducting terminals mounted in insulated relation to each other within the handle and adapted to constitute a switch in a primary electrical circuit, and a movable. element enclosed by the handle to open and to close the primary circuit across the pair of terminals, and exterior to the handle and connected therewith, a primary circuit and a secondary circuit interconnected by a transformer, variable resistance in the secondary operated by flow of current to vary the secondary isclosed.

circuit, and a motor nonan'r n. 3 m. 

